Heat 1 tablespoon oil in a non-stick frying pan over medium-high heat. Add sausages. Cook, turning often, for 15 minutes or until cooked through. Transfer to a plate lined with paper towel. Slice sausages.
Heat 1 tablespoon oil in a large heavy-based saucepan over medium-high heat. Add onion, garlic and capsicum. Cook for 3 minutes or until soft. Add tomato passata and 4 cups cold water. Bring to the boil.
Add risoni and cook, stirring, for 10 minutes or until risoni is just tender. Add oregano and season with salt and pepper. Stir sausages through warm risoni. Cover to keep warm.
Toss rocket, parmesan and remaining 1 tablespoon oil together in a bowl. Season with salt and pepper. Spoon risoni mixture into bowls. Top with rocket salad and serve.